fixed_size_vector.h revision 4927ee586656424c827920876673228fbdcf27c3 
1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef CHRE_UTIL_FIXED_SIZE_VECTOR_H_
18#define CHRE_UTIL_FIXED_SIZE_VECTOR_H_
19
20#include <type_traits>
21
22namespace chre {
23
24template<typename ElementType, size_t kCapacity>
25class FixedSizeVector {
26 public:
27  /**
28   * Obtains a pointer to the underlying storage for the vector.
29   *
30   * @return A pointer to the storage used for elements in this vector.
31   */
32  ElementType *data();
33
34  /**
35   * Obtains a const pointer to the underlying storage for the vector.
36   *
37   * @return A const pointer to the storage used for elements in this vector.
38   */
39  const ElementType *data() const;
40
41  /**
42   * Obtains the number of elements currently stored in the static vector.
43   *
44   * @return The number of elements currently stored in the vector.
45   */
46  size_t size() const;
47
48  /**
49   * Obtains the maximum number of elements that can be stored in the static
50   * vector.
51   *
52   * @return The maximum capacity of the vector as defined by the template
53   * argument.
54   */
55  size_t capacity() const;
56
57  /**
58   * Determines whether the vector is empty or not.
59   *
60   * @return Returns true if the vector is empty.
61   */
62  bool empty() const;
63
64  /**
65   * Determins whether the vector is full or not.
66   *
67   * @return Returns true if the vector is full.
68   */
69  bool full() const;
70
71  /**
72   * Pushes an element onto the back of the vector. It is illegal to push an
73   * item onto a full vector. The user of the API must check the return of the
74   * full() function prior to pushing another element.
75   *
76   * @param The element to push onto the vector.
77   */
78  void push_back(const ElementType& element);
79
80  /**
81   * Constructs an element onto the back of the vector. It is illegal to
82   * construct an item onto a full vector. The user of the API must check the
83   * return of the full() function prior to constructing another element.
84   *
85   * @param The arguments to the constructor
86   */
87  template<typename... Args>
88  void emplace_back(Args&&... args);
89
90  /**
91   * Obtains an element of the vector given an index. It is illegal to index
92   * this vector out of bounds and the user of the API must check the size()
93   * function prior to indexing this vector to ensure that they will not read
94   * out of bounds.
95   *
96   * @param The index of the element.
97   * @return The element.
98   */
99  ElementType& operator[](size_t index);
100
101  /**
102   * Obtains a const element of the vector given an index. It is illegal to
103   * index this vector out of bounds and the user of the API must check the
104   * size() function prior to indexing this vector to ensure that they will not
105   * read out of bounds.
106   *
107   * @param The index of the element.
108   * @return The element.
109   */
110  const ElementType& operator[](size_t index) const;
111
112 private:
113  //! Storage for vector elements. To avoid static initialization of members,
114  //! std::aligned_storage is used.
115  typename std::aligned_storage<sizeof(ElementType),
116      alignof(ElementType)>::type mData[kCapacity];
117
118  //! The number of elements in the vector. This will never be more than
119  //! kCapacity.
120  size_t mSize = 0;
121};
122
123}  // namespace chre
124
125#include "chre/util/fixed_size_vector_impl.h"
126
127#endif  // CHRE_UTIL_FIXED_SIZE_VECTOR_H_
128